Aluminum casting alloys



United States Patent 9 ALUMINUM CASTING ALLOYS Hugh S. Cooper, Shaker Heights, Ohio, assignor to Willham F. Jobbins, Incorporated, Aurora, 111., a corporation of Illinois No Drawing. Application October 4, 1954, Serial No. 460,243

5 Claims. (Cl. 75143) This invention relates to aluminum alloys and more particularly to aluminum casting alloys having improved properties.

Early in the art aluminum-copper casting alloys were commonly used commercially and later these were largely replaced by aluminum-silicon casting alloys. The aluminum-silicon casting alloys are usually classed as the low silicon alloys which generally contain about 3% to 8% silicon and those containing 8% or 9% silicon to or so of silicon and when sand cast and without special heat treatment such alloys usually had relatively low elongation or relatively low tensile and yield strength or both.

There are also a number of aluminum casting alloys containing copper in amounts from 3% or so to 7% but these have a silicon content of at least 3% and when cast in sand have a relatively low elongation that is of the order of 2% or 3%.

It has been thought that such aluminum-copper-silicon alloys should contain about 3% or more of silicon to give the alloy suflicient fluidity to have the desirable casting properties.

The United States Patent of Alfred von Zeerleder No. 1,480,846 is directed to aluminum-copper alloy to which 1.5% or more of iron is added, copper being present in an amount twice that of the iron. The purpose of the Von Zeerleder alloy was to increase the tensile strength of casting alloys and yet obtain a ductility not attainable with prior aluminum-copper casting alloys.

It is an object of the present invention to produce an aluminum-copper-iron casting alloy having relatively high strength, relatively high elongation and relatively high fluidity, and which alloy may be readily made from secondary metal.

I have discovered that when small amounts of both silicon and titanium are present in an aluminum-copperiron alloy, a casting alloy having greatly improved properties is obtained.

According to my discovery, an alloy containing copper in an amount from about 2.0% to 5.0%, iron in an amount from 1.5% to 2.5%, silicon in an amount from about .2% to 1.5%, and titanium in an amount from about .05% to .3%, when sand cast, gives relatively high tensile strength and high yield point and also has relatively high elongation and fluidity compared to an aluminumcopper-iron alloy but without the addition of proper amounts of silicon and titanium.

In the present alloy it has been found that even .2% of silicon improves the tensile strength and yield point and greatly improves the elongation and fluidity. Silicon should be present in the alloy in an amount from about .2% to about 2% and the preferred amount is from about .5% to about 1.25%.

Iron should be present in the alloy in an amount from about 1.5% to about 2.5% or 3%, preferably about 2%. As the amount of iron exceeds 2.5 and approaches 3% the elongation of the alloy substantially decreases.

Copper should be present in the alloy in the amount of about 2% to about 5% and preferably in the range of about 3% to 4.5%.

Titanium should be present in the alloy in an amount from .05 to .3% and preferably from about .1% to about .2%.

2,811,439 Patented Oct. 29, 1957 Example 1 An aluminum-copper-iron alloy containing 4% copper,

2% iron, 1% silicon and about .15% titanium was cast alloy, at a definite temperature such as 1325 F., gives a comparative value for the fluidity of the metal.

Example 2 An aluminum alloy containing 4% copper, 2% iron, .2% silicon and .15 titanium was cast in sand mold and upon testing the alloy as cast it had a tensile strength of 28,400 pounds p. s. i., 14,000 pounds yield point, an elongation of 10% and a fluidity of 7.5 inches at a temperature of 1325 F.

Example 3 An alloy containing 3% copper, 2% iron and 1% silicon was made and cast in a sand mold and the alloy as cast had a tensile strength of 27,000 pounds p. s. i., a yield point of 11,000 pounds p. s. i., an elongation of 9% and a fluidity of 8.5 inches at 1325 F.

Alloys containing copper and iron in the amounts set forth in Examples 1 and 3 and having silicon present in an amount less than .1% have a fluidity of about 4.5 inches at a temperature of 1325 F.

It will thus be seen that utilizing small amounts of silicon and titanium in aluminum-copper-iron alloys gives a casting alloy which has excellent tensile strength and an elongation from 6% to 10% together with a fluidity in excess of 7.5 inches at 1325 F.

The desirable effects of the combination of copper, silicon, iron and titanium enable one to obtain many of the benefits of the aluminum-copper and aluminum-silicon alloys while still maintaining the high strength and ductility of the metal as cast in sand molds.

It will also be seen that valuminumcopper-iron alloys coming within the present invention may be readily made from secondary metals not heretofore usable on account of its high iron content. Other elements may be present in the alloy as impurities or as ingredients in amounts not subversive to the above mentioned characteristics.

Furthermore, it is to be understood that various modifications of the alloys disclosed herein can be made without departing from our invention as defined in the appended claims.

Having described my invention, I claim:

1. An aluminum casting alloy consisting essentially of aluminum, 2.0% to 5% copper, 1.5 %to 2.5% iron, .2% to 2% silicon and .05% to .3% titanium.

2. The alloy of claim 1 in which the copper content is from 3% to 4.5%.

3. The alloy of claim 1 in which the silicon is present in an amount from .5% to about 1.25

4. The alloy of claim 1 in which the titanium content is from .1% to 25%.

5. An aluminum casting alloy consisting essentially of aluminum, 3% to 4.5% of copper, 1.5% to 2.5 of iron, .5% to about 1.25% of silicon and .1% to .25% of titanium.

.- References Cited in the file of this patent Aluminum Alloys, published by Federated Metals Division, 'American Smelting and Refining Co., page 3. Qopy received in Patent Otfice March 29, 1943. 

1. AN ALUMINUM CASTING ALLOY CONSISTING ESSENTIALLY OF ALUMINUM, 2.0% TO 5% COPPER 1.5% IRON, .2% TO 2% SILICON AND .05% TO 3% TITANIUM. 